The Transgenic Mouse/ES Cell Shared Resource (TMESCSR) facilitates the generation, maintenance, and storage of genetically modified mice, thereby providing useful animal models for the study of diabetes, obesity, and the mechanisms controlling carbohydrate, fat, and protein homeostasis. This facility has been in operation and supported by the VDRTC for nearly 18 years and currently provides six different service clusters related to the production and maintenance of genetically modified mice. During its history, the TMESCSR has served 182 different investigators by generating over 2400 transgenic founder mice from 660 distinct DNA constructs and 4100 chimeric mice from 700 different ES cell clones. The Shared Resource has further assisted in the generation of at least 101 different genetically modified mice using homologous recombination in mouse embryonic stem cells (mESCs). Many of the genetically modified mice have been used by investigators at Vanderbilt and other institutions to gain insight into the function and development of pancreatic islets, the liver, skeletal muscle, and fat and to study complications of diabetes such as diabetic nephropathy. The resource has developed several new services over the past funding cycle, including the ability to perform Recombinase-mediated Cassette Exchange (RMCE) and BAC Recombineering. By providing state-of-the-art, cost-effective and quality-controlled services this resource continues to be an important asset for both DTRC-affiliated investigators and others who indirectly benefit from this resource.